Selective oxidation of O-isopropylidene derivatives of diols to 2-hydroxy ketones employing dioxiranes

Employing dimethyldioxirane (1a) or methyl(trifluoromethyl)dioxirane (1b), the direct conversion of O-isopropylidene derivatives of 1,2-diols into the corresponding 2-hydroxy ketones can be achieved in high yield and under mild conditions; optically active acetonides are transformed into homochiral 2-hydroxy ketones in high optical yield, and with preservation of configuration at the C-*-OH chiral center proximal to that undergoing oxidation to carbonyl. The diacetonide of 1,4-Diphenylbutan-1,2:3,4-tetraol could be selectively converted into 1,4-diphenyl-1-oxo-2-hydroxy 3,4-acetonide, with removal of just one acetonide moiety